This invention relates to compositions containing proanthocyanidin, drinks, foods, cosmetics and medicaments containing these compositions and a method for stabilizing proanthocyanidin.
It is known that proanthocyanidin, which is a substance contained in a number of plants and having a strong antioxidant effect, is susceptible to oxidation and quickly undergoes oxidative polymerization in the presence of oxygen, thereby showing a color change.
Conventional techniques to stabilize proanthocyanidin mainly include addition of potassium pyrosulfite (e.g., to wine) and addition of ascorbic acid (e.g., to apple juice).
JP-A-6-336420 discloses cosmetics containing sodium hydrogensulfite, 1-hydroxyethane-1,1-disulfonic acid, diethylenetriamine pentaacetic acid or phytic acid to prevent the color change of proanthocyanidin with the passage of time (the term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d).
On the other hand, examples of methods for stabilizing polyphenol or preventing its color change or compositions for stabilizing polyphenol or preventing its color change are as follows: (1) a method for preventing the color change of polyphenol by adding a porphyrin zinc complex and an organic reducing agent to polyphenol as disclosed in JP-B-8-2819 (the term xe2x80x9cJP-Bxe2x80x9d as used herein means an xe2x80x9cexamined Japanese patent publicationxe2x80x9d); (2) skin cosmetics containing a polyphenol compound together with a sucrose higher fatty acid ester disclosed in JP-A-5-112441; (3) skin cosmetics containing a polyphenol compound together with an alkyl glucoside disclosed in JP-A-5-163131; and (4) a method for preventing the color change of skin preparations for an external use which contain a polyphenol compound carrying at least 3 phenolic hydroxyl groups by adding a polyhydric alcohol or a sugar to the preparations disclosed in Japanese Patent No. 2,744,572.
An object of the invention is to provide proanthocyanidin-containing compositions having excellent proanthocyanidin stability, as well as drinks, foods, cosmetics and medicaments containing these compositions, and a method for stabilizing proanthocyanidin so as to prevent the color change, etc. caused by the oxidative polymerization, etc., thereof.
The invention provides compositions containing proanthocyanidin and a vitamin B6 derivative or its salt, and drinks, foods, cosmetics and medicaments containing these compositions.
The invention further provides a method for stabilizing proanthocyanidin characterized by blending proanthocyanidin with a vitamin B6 derivative or its salt.
The invention furthermore provides proanthocyanidin stabilizers containing a vitamin B6 derivative or its salt.
Particular examples of the vitamin B6 derivative include pyridoxine, pyridoxal, pyridoxamine and phosphates thereof such as pyridoxal-5-phosphate. Pyridoxine, pyridoxal and pyridoxamine are compounds represented by the following general formula (I). 
In the above formula, R1 represents xe2x80x94CH2OH (pyridoxine), xe2x80x94CHO (pyridoxal), or xe2x80x94CH2NH2 (pyridoxamine).
Examples of the salt of the vitamin B6 derivative include inorganic acid salts (hydrochloride, sulfate, nitrate, phosphate and the like) and organic acid salts (maleate, fumarate, citrate, acetate and the like) of the vitamin B6 derivative, preferably dietary, cosmetically or pharmaceutically acceptable salts. The vitamin B6 derivative or its salt may exist in the form of a hydrate or a solvate in some cases.
The vitamin B6 derivative or its salt can be synthesized by a known method described in, for example, Kagaku-Daijiten (ed. by Kagaku-Daijiten Henshu Iinkai, vol. 7, p. 406, Aug. 5, 1962). Alternatively, a commercially available product may be employed.
Examples of proanthocyanidin include compounds having two or more flavan-7-ol derivatives, which are represented by the following general formula (II), bonded together. 
In the above formula, R3 and R4 are the same or different and each represents hydrogen, a hydroxyl group, a galloyloxy group or a glucopyranosyl group; and R2, R5, R6, R7, R8 and R9 are the same or different and each represents hydrogen or a hydroxyl group.
Preferable examples of the flavan-7-ol derivative represented by the general formula (II) include catechin, epicatechin, gallocatechin, epigallocatechin, afzelechin and epiaflezechin.
With respect to proanthocyanidin, a carbon atom of one flavan-7-ol derivative may be bonded to a carbon atom of another flavan-7-ol derivative through a single bond or an ether bond via an oxygen atom, etc. Any carbon or oxygen atom in formula (II) may participate in forming these bonds, although in the case of an ether bond, the bond is preferably formed via a hydroxyl group of the flavan-7-ol derivative. The flavan-7-ol derivatives which are bonded together to form proanthocyanidin may be either the same or different from each other.
The following general formulae (III-a), (III-b) and (III-c) show preferred examples of the bonding modes of these flavan-7-ol derivatives. 
In the above formulae, R3a, R4a, R3b, R4b, R3c, R4c, R3d, R4d, R3e, R4e, R3f, and R4f, are the same or different and each represents hydrogen, a hydroxyl group, a galloyloxy group or a glucopyranosyloxy group; and R5a, R6a, R7a, R8a, R9a, R2b, R5b, R7b, R8b, R9b, R5c, R6c, R7c, R8c, R9d, R2d, R5d, R6d, R7d, R8d, R9d, R5e, R6e, R7e, R8e, R9e, R2f, R5f, R7f, R8f, and R9f are the same or different and each represents hydrogen or a hydroxyl group.
As the proanthocyanidin, it is preferable to use a compound having from 2 to 10, more preferably from 2 to 4, flavan-7-ol structural units as described above.
Examples of dimers of flavan-7-ol derivatives include epicatechin-catechin bonded compounds such as epicatechin-(4xcex2xe2x86x928)-catechin, epicatechin dimers such as epicatechin-(4xcex2xe2x86x926)-epicatechin and epicatechin-(xcex2xe2x86x928)-epicatechin (procyanidin B-2), and catechin-catechin dimers such as catechin-(4xcex1xe2x86x928)-catechin. Examples of trimers of flavan-7-ol derivatives include epicatechin trimers such as epicatechin-(4xcex2xe2x86x928)-epicatechin-(4xcex2xe2x86x928)-epicatechin and epicatechin-(4xcex2xe2x86x928)-epicatechin-(4xcex2xe2x86x926)-epicatechin, catechin trimers such as catechin-(4xcex1xe2x86x928)-catechin-(4xcex1xe2x86x928)-catechin, and mixed epicatechin-catechin trimers such as epicatechin-(4xcex2xe2x86x928)-epicatechin-(4xcex2xe2x86x928)-catechin.
In addition, compounds wherein gallic acid or sugars (glucose, rhamnose and the like) are bonded to the above-described compounds also fall within the concept of the proanthocyanidin as used in the invention.
Proanthocyanidin has various isomers including optical isomers and all of these isomers and mixtures thereof may be utilized in the present invention.
Proanthocyanidin can be obtained by extraction (and optional purification) from various plants such as a grape, an apple, a barley, a persimmon, a coconut, a cacao, a pine, a blueberry, a strawberry, an adzuki bean and a peanut, which belong to the genera Vitis, Malus, Hordeum, Diospyros, Cocos, Theobroma, Pinus, Vaccinium, Fragaria, Phaseolus, Arachis, etc. It is also possible to obtain proanthocyanidin optionally by purifying from fermented products of these extracts, such as a wine, a cider, a beer and the like.
The extraction and purification from a plant may be carried out in the following manner, which is known in the art (Chemical and Pharmaceutical Bulletin, 38: 3218, 1990 and ibid., 40: 889-898, 1992; Acta Derm. Venereol. (Stockh.), 78, 428 (1998) or the like).
A plant material (a fruit, a seed, a leaf, a stem, a root, a rhizome, etc.) is harvested at an appropriate time and then optionally dried by, for example, usual air-drying to give a material to be extracted. The starting material is ground or cut into pieces and then extracted by a solvent. As the extraction solvent, hydrophilic or lipophilic solvents such as water, alcohols (ethanol, methanol, isopropyl alcohol, etc.), ketones (acetone, methyl ethyl ketone, etc.), or esters (methyl acetate, ethyl acetate, etc.) may be used either alone or as a solvent mixture. The extraction temperature usually ranges from 0 to 100xc2x0 C., preferably from 5 to 50xc2x0 C.
The extraction is carried out for 1 hour to about 10 days. The solvent is used in an amount usually 1 to 30 times by weight, preferably 5 to 10 times by weight, based upon that of the dry material. The extraction may be carried out either under stirring or allowing to stand in an immersed state. The extraction procedure may be repeated twice or more, if necessary.
From the crude extract obtained above, insoluble residue is removed by filtration or centrifugation. Proanthocyanidin may be purified from the thus obtained extract, plant press juice or sap by well-understood methods known for separation and purification of crude drugs, preferably using biphasic solvent partition, column chromatography, preparative high-performance liquid chromatography, etc. either alone or in combination. The biphasic solvent partition can be carried out by, for example, extracting oily components and pigments from the above-mentioned extract with n-hexane, petroleum ether, etc. and eliminating the thus obtained extract, or by distributing the extract into a solvent (n-butanol, methyl ethyl ketone, etc.) and water and collecting proanthocyanidin from the solvent phase. The column chromatography method is exemplified by an ion exchange chromatography method with the use of Amberlite IR-120B, Amberlite IRA-402, etc. as a carrier, an adsorption column chromatography method with the use of normal phase silica gel, reversed phase silica gel, Diaion HP-20, Sepabeads SP-207, etc. as a carrier, and a gel filtration method with the use of Sephadex LH-20, etc. as a carrier. These can be used either alone or in combination repeatedly. Examples of the preparative high-performance liquid chromatography method include a reversed phase column chromatography method with the use of octadecyl silica, etc. and a normal phase column chromatography method with the use of silica gel, etc.
By the purification method as described above, water soluble ionic substances (salts, etc.), nonionic substances (saccharides, polysaccharides, etc.), oils, pigments, etc. are removed from the crude extract and thus proanthocyanidin is purified.
Proanthocyanidin originating in grape seeds can be obtained according to the method similar to that described in Acta Derm. Venereol. (stockh.), 78, 428 (1998).
As a method for producing proanthocyanidin by synthesis, Journal of the Chemical Society (Perkin Transaction I: 1535-1543, 1983) reports a method for producing an epicatechin or catechin dimer. Thus, various kinds of proanthocyanidin can be synthesized by the method reported in the above document or by the reference thereto.
An alcoholic fermentation product from a plant extract containing proanthocyanidin can be obtained by a known method as follows. In the case of a fermentative liquor of the simple fermentation type such as wine or cider, a fruit juice is subjected to alcoholic fermentation with the use of yeast. To produce a red wine from a grape juice, for example, grape fruits are ground and an antioxidant is added thereto. After adding 2 to 5% of yeast mash thereto, the main fermentation is carried out for 7 to 10 days. Next, the fermented liquor is pressed and the pericarp and the sediments are removed. Then the residue is transferred into a tapped barrel provided with a fermentation bung and subjected to after-fermentation at about 10xc2x0 C. until the residual sugar content is reduced to 0.2% or less. After separating the sediments (tartar, tannin, protein, etc.), aging is continued for additional several years to give a wine product. In the case of a fermentative liquor of the multiple fermentation type such as beer, cereal starch employed as the starting material is first saccharified with amylase and then subjected to alcoholic fermentation. To produce beer by using barley as the major starting material, for example, wort is prepared from malt and water and then yeast is added thereto followed by fermentation. The main fermentation is carried out at 7 to 10xc2x0 C. for 10 days. Then the fermented liquor is transferred into a storage tank and the after-fermentation is carried out at 0 to 2xc2x0 C. for 60 days. After the completion of after-fermentation, the fermented liquor is filtered or sterilized under heating to give the desired fermentation product.
As a method for purifying proanthocyanidin from these alcoholic fermentation products, the methods discussed for crude extract, plant press juice or sap may be used so as to remove undesired water-soluble ionic substances (salts, etc.), nonionic substances (saccharides, polysaccharides, etc.), oils, pigments, etc.
When proanthocyanidin is used as a component in the composition according to the invention, proanthocyanidin of a single type or a mixture of two or more types may be used. Particular examples of the proanthocyanidin include grape seed extract proanthocyanidin, a purified red wine extract, proanthocyanidin originating in an apple, proanthocyanidin originating in a pine and purified proanthocyanidin oligomers.
The proanthocyanidin content in the composition of the invention may be determined depending on use, etc. without restriction. In the case of compositions to be used in drinks, foods, cosmetics, medicaments, etc., for example, the proanthocyanidin content ranges preferably from 0.01 to 20% by weight, more preferably form 0.1 to 10% by weight, based on the whole composition (the total weight of all of the components).
The content of the vitamin B6 derivative or its salt in the composition of the invention may be determined depending on use, the type of proanthocyanidin, etc. without restriction. In the case of compositions to be used in drinks, foods, cosmetics, medicaments, etc., for example, the content ranges preferably from 0.001 to 1% by weight, more preferably form 0.005 to 0.5% by weight and further preferably from 0.01 to 0.3% by weight, based on the whole composition (the total weight of all of the components).
The composition of the invention may further contain antioxidants such as sodium hydrogensulfite, sodium pyrosulfite, ascorbic acid, erythorbic acid and tocopherols. Moreover, the composition of the invention may furthermore contain additives etc. appropriate for each of drinks, foods, cosmetics, medicaments, etc.
Now, drinks, foods, cosmetics and medicaments according to the invention each containing the composition of the invention will be described.
The drinks of the invention are desirably in the form of liquors such as fruit liquors, soft drinks, health drinks, tonic drinks, vitamin drinks, fruit drinks, etc.
The drinks of the invention can be obtained by adding the vitamin B6 derivative or its salt to drinks containing proanthocyanidin, for example, (1) juices which are prepared by pressing plant materials and taken as such, e.g., fruit juices such as an apple juice, a grape juice and a blueberry juice; (2) drinks which are obtained by extracting from plant materials or processed products thereof with a hot water, e.g., various teas such as a barley tea, a green tea, an oolong tea, a black tea, a persimmon leaf tea and a Chinese matrimony vine tea; (3) drinks which are prepared by alcoholic fermentation of plant press juices, e.g., fruit liquors such as wine, cider and a blueberry liquor and alcoholic drinks such as beer and sparkling liquors; and (4) drinks which are prepared by immersing fruits in alcohol and extracting the extract, e.g., a Chinese quince liquor and a plum liquor. Soft drinks, health drinks and tonic drinks can also be produced by blending proanthocyanidin and the vitamin B6 derivative or its salt optionally together with, for example, proteins, saccharides, fats, trace elements, vitamins, emulsifiers and perfumes and processing in the conventional manner.
The foods of the invention are in the form of tablets, capsules, powders, pills, jellies, frozen foods, powdery foods, sheet foods, bottled foods, canned foods, retort foods, etc. In addition, they may be processed into spontaneous liquid foods, half-digested nutritional foods, elemental nutritional foods and the like. The foods according to the invention preferably involve processed fruit products such as various jams and syruped fruits.
The foods of the invention can be produced by blending proanthocyanidin and the vitamin B6 derivative or its salt with materials commonly employed in foods, for example, proteins, saccharides, fats, trace elements, vitamins, emulsifiers and perfumes and processing in the conventional manner.
The cosmetics of the invention may be in the form of liquids, gels, emulsions, solids such as creams, etc. Examples of the cosmetics according to the invention include lotions, cosmetic lotions, milky lotions, creams, packs, hair growth stimulant tonics and shampoos.
The cosmetics of the invention can be produced by blending proanthocyanidin and the vitamin B6 derivative or its salt with materials commonly employed in cosmetics, for example, solid fats, semi-solid fats, liquid oils, humectants, emollients, surfactants, water-soluble polymers, fat-soluble polymers, organic or inorganic pigments, organic powders, UV absorbers, anti-inflammatory substances, refrigerants, preservatives, antioxidants, pH regulating agents (a citrate buffer solution, etc.), bactericides, vitamins, crude drugs and components thereof, skin softeners, perfumes, colorants, ethanol and purified water and processing in the conventional manner.
The medicaments of the invention are in the form of tablets, capsules, powders, pills, powders, fine powders, granules, syrups, troches, etc.
The medicaments of the invention can be produced by blending proanthocyanidin and the vitamin B6 derivative or its salt optionally with other active ingredients of medicaments and processing in the conventional manner usually with the use of excipients. Examples of the excipients include saccharides (sorbitol, lactose, glucose, etc.), dextrin, starch, inorganic matters (calcium carbonate, calcium sulfate, etc.), a crystalline cellulose, a distilled water, a sesame oil, a corn oil, an olive oil and a cottonseed oil. Any excipient may be used so long as it is employed in general. To process into preparations, it is also possible to use additives such as binders, lubricants, dispersing agents, suspending agents, emulsifiers, diluents, buffers, antioxidants and bacteriostatic agents.
The compositions according to the invention and the drinks, foods, cosmetics and medicaments according to the invention containing these compositions are excellent in the stability of proanthocyanidin and suffer from little color change of proanthocyanidin with the passage of time.
The invention further provides a method for stabilizing proanthocyanidin characterized by blending proanthocyanidin with a vitamin B6 derivative or its salt. This method can be carried out by setting various conditions including the content of the vitamin B6 derivative or its salt as defined above with respect to the compositions of the invention and the drinks, foods, cosmetics and medicaments of the invention.
The invention furthermore provides proanthocyanidin stabilizers containing a vitamin B6 derivative or its salt. Various conditions including the content of the vitamin B6 derivative or its salt can be set as defined above with respect to the compositions of the invention and the drinks, foods, cosmetics and medicaments of the invention.